 /*
  * $Header: /cvshome/build/org.osgi.framework/src/org/osgi/framework/ServicePermission.java,v 1.15 2007/02/20 00:06:02 hargrave Exp $
  *
  * Copyright (c) OSGi Alliance (2000, 2007). All Rights Reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  * http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 package org.osgi.framework;

 import java.io.IOException ;
 import java.security.*;
 import java.util.Enumeration ;
 import java.util.Hashtable ;

 /**
  * A bundle's authority to register or get a service.
  * <ul>
  * <li>The <code>ServicePermission.REGISTER</code> action allows a bundle to
  * register a service on the specified names.
  * <li>The <code>ServicePermission.GET</code> action allows a bundle to
  * detect a service and get it.
  * </ul>
  * Permission to get a service is required in order to detect events regarding
  * the service. Untrusted bundles should not be able to detect the presence of
  * certain services unless they have the appropriate
  * <code>ServicePermission</code> to get the specific service.
  *
  * @version $Revision: 1.15 $
  */

 final public class ServicePermission extends BasicPermission {
     static final long serialVersionUID = -7662148639076511574L;
     /**
      * The action string <code>get</code> (Value is "get").
      */
     public final static String GET = "get";
     /**
      * The action string <code>register</code> (Value is "register").
      */
     public final static String REGISTER = "register";

     private final static int ACTION_GET = 0x00000001;
     private final static int ACTION_REGISTER = 0x00000002;
     private final static int ACTION_ALL = ACTION_GET
                                                             | ACTION_REGISTER;
     private final static int ACTION_NONE = 0;
     /**
      * The actions mask.
      */
     private transient int action_mask = ACTION_NONE;

     /**
      * The actions in canonical form.
      *
      * @serial
      */
     private String actions = null;

     /**
      * Create a new ServicePermission.
      *
      * <p>
      * The name of the service is specified as a fully qualified class name.
      *
      * <pre>
      * ClassName ::= &lt;class name&gt; | &lt;class name ending in &quot;.*&quot;&gt;
      * </pre>
      *
      * Examples:
      *
      * <pre>
      * org.osgi.service.http.HttpService
      * org.osgi.service.http.*
      * org.osgi.service.snmp.*
      * </pre>
      *
      * <p>
      * There are two possible actions: <code>get</code> and
      * <code>register</code>. The <code>get</code> permission allows the
      * owner of this permission to obtain a service with this name. The
      * <code>register</code> permission allows the bundle to register a
      * service under that name.
      *
      * @param name class name
      * @param actions <code>get</code>,<code>register</code> (canonical
      * order)
      */

     public ServicePermission(String name, String actions) {
         this(name, getMask(actions));
     }

     /**
      * Package private constructor used by ServicePermissionCollection.
      *
      * @param name class name
      * @param mask action mask
      */
     ServicePermission(String name, int mask) {
         super(name);

         init(mask);
     }

     /**
      * Called by constructors and when deserialized.
      *
      * @param mask action mask
      */
     private void init(int mask) {
         if ((mask == ACTION_NONE) || ((mask & ACTION_ALL) != mask)) {
             throw new IllegalArgumentException ("invalid action string");
         }

         action_mask = mask;
     }

     /**
      * Parse action string into action mask.
      *
      * @param actions Action string.
      * @return action mask.
      */
     private static int getMask(String actions) {
         boolean seencomma = false;

         int mask = ACTION_NONE;

         if (actions == null) {
             return mask;
         }

         char[] a = actions.toCharArray();

         int i = a.length - 1;
         if (i < 0)
             return mask;

         while (i != -1) {
             char c;

             // skip whitespace
 while ((i != -1)
                     && ((c = a[i]) == ' ' || c == '\r' || c == '\n'
                             || c == '\f' || c == '\t'))
                 i--;

             // check for the known strings
 int matchlen;

             if (i >= 2 && (a[i - 2] == 'g' || a[i - 2] == 'G')
                     && (a[i - 1] == 'e' || a[i - 1] == 'E')
                     && (a[i] == 't' || a[i] == 'T')) {
                 matchlen = 3;
                 mask |= ACTION_GET;

             }
             else
                 if (i >= 7 && (a[i - 7] == 'r' || a[i - 7] == 'R')
                         && (a[i - 6] == 'e' || a[i - 6] == 'E')
                         && (a[i - 5] == 'g' || a[i - 5] == 'G')
                         && (a[i - 4] == 'i' || a[i - 4] == 'I')
                         && (a[i - 3] == 's' || a[i - 3] == 'S')
                         && (a[i - 2] == 't' || a[i - 2] == 'T')
                         && (a[i - 1] == 'e' || a[i - 1] == 'E')
                         && (a[i] == 'r' || a[i] == 'R')) {
                     matchlen = 8;
                     mask |= ACTION_REGISTER;

                 }
                 else {
                     // parse error
 throw new IllegalArgumentException ("invalid permission: "
                             + actions);
                 }

             // make sure we didn't just match the tail of a word
 // like "ackbarfregister". Also, skip to the comma.
 seencomma = false;
             while (i >= matchlen && !seencomma) {
                 switch (a[i - matchlen]) {
                     case ',' :
                         seencomma = true;
                     /* FALLTHROUGH */
                     case ' ' :
                     case '\r' :
                     case '\n' :
                     case '\f' :
                     case '\t' :
                         break;
                     default :
                         throw new IllegalArgumentException (
                                 "invalid permission: " + actions);
                 }
                 i--;
             }

             // point i at the location of the comma minus one (or -1).
 i -= matchlen;
         }

         if (seencomma) {
             throw new IllegalArgumentException ("invalid permission: " + actions);
         }

         return mask;
     }

     /**
      * Determines if a <code>ServicePermission</code> object "implies" the
      * specified permission.
      *
      * @param p The target permission to check.
      * @return <code>true</code> if the specified permission is implied by
      * this object; <code>false</code> otherwise.
      */

     public boolean implies(Permission p) {
         if (p instanceof ServicePermission) {
             ServicePermission target = (ServicePermission) p;

             return (((action_mask & target.action_mask) == target.action_mask) && super
                     .implies(p));
         }

         return (false);
     }

     /**
      * Returns the canonical string representation of the actions. Always
      * returns present actions in the following order: <code>get</code>,
      * <code>register</code>.
      *
      * @return The canonical string representation of the actions.
      */
     public String getActions() {
         if (actions == null) {
             StringBuffer sb = new StringBuffer ();
             boolean comma = false;

             if ((action_mask & ACTION_GET) == ACTION_GET) {
                 sb.append(GET);
                 comma = true;
             }

             if ((action_mask & ACTION_REGISTER) == ACTION_REGISTER) {
                 if (comma)
                     sb.append(',');
                 sb.append(REGISTER);
             }

             actions = sb.toString();
         }

         return (actions);
     }

     /**
      * Returns a new <code>PermissionCollection</code> object for storing
      * <code>ServicePermission<code> objects.
      *
      * @return A new <code>PermissionCollection</code> object suitable for storing
      * <code>ServicePermission</code> objects.
      */
     public PermissionCollection newPermissionCollection() {
         return (new ServicePermissionCollection());
     }

     /**
      * Determines the equalty of two ServicePermission objects.
      *
      * Checks that specified object has the same class name and action as this
      * <code>ServicePermission</code>.
      *
      * @param obj The object to test for equality.
      * @return true if obj is a <code>ServicePermission</code>, and has the
      * same class name and actions as this
      * <code>ServicePermission</code> object; <code>false</code>
      * otherwise.
      */
     public boolean equals(Object obj) {
         if (obj == this) {
             return (true);
         }

         if (!(obj instanceof ServicePermission)) {
             return (false);
         }

         ServicePermission p = (ServicePermission) obj;

         return ((action_mask == p.action_mask) && getName().equals(p.getName()));
     }

     /**
      * Returns the hash code value for this object.
      *
      * @return Hash code value for this object.
      */

     public int hashCode() {
         return (getName().hashCode() ^ getActions().hashCode());
     }

     /**
      * Returns the current action mask. Used by the ServicePermissionCollection
      * object.
      *
      * @return The actions mask.
      */
     int getMask() {
         return (action_mask);
     }

     /**
      * WriteObject is called to save the state of this permission to a stream.
      * The actions are serialized, and the superclass takes care of the name.
      */

     private synchronized void writeObject(java.io.ObjectOutputStream s)
             throws IOException {
         // Write out the actions. The superclass takes care of the name
 // call getActions to make sure actions field is initialized
 if (actions == null)
             getActions();
         s.defaultWriteObject();
     }

     /**
      * readObject is called to restore the state of this permission from a
      * stream.
      */
     private synchronized void readObject(java.io.ObjectInputStream s)
             throws IOException , ClassNotFoundException {
         // Read in the action, then initialize the rest
 s.defaultReadObject();
         init(getMask(actions));
     }
 }

 /**
  * Stores a set of ServicePermission permissions.
  *
  * @see java.security.Permission
  * @see java.security.Permissions
  * @see java.security.PermissionCollection
  */

 final class ServicePermissionCollection extends PermissionCollection {
     static final long serialVersionUID = 662615640374640621L;
     /**
      * Table of permissions.
      *
      * @serial
      */
     private Hashtable permissions;

     /**
      * Boolean saying if "*" is in the collection.
      *
      * @serial
      */
     private boolean all_allowed;

     /**
      * Creates an empty ServicePermissions object.
      */

     public ServicePermissionCollection() {
         permissions = new Hashtable ();
         all_allowed = false;
     }

     /**
      * Adds a permission to the <code>ServicePermission</code> objects using
      * the key for the hash as the name.
      *
      * @param permission The Permission object to add.
      *
      * @throws IllegalArgumentException If the permission is not a
      * ServicePermission object.
      * @throws SecurityException If this
      * <code>ServicePermissionCollection</code> object has been marked
      * read-only.
      */

     public void add(Permission permission) {
         if (!(permission instanceof ServicePermission))
             throw new IllegalArgumentException ("invalid permission: "
                     + permission);
         if (isReadOnly())
             throw new SecurityException ("attempt to add a Permission to a "
                     + "readonly PermissionCollection");

         ServicePermission sp = (ServicePermission) permission;
         String name = sp.getName();

         ServicePermission existing = (ServicePermission) permissions.get(name);

         if (existing != null) {
             int oldMask = existing.getMask();
             int newMask = sp.getMask();
             if (oldMask != newMask) {
                 permissions.put(name, new ServicePermission(name, oldMask
                         | newMask));
             }
         }
         else {
             permissions.put(name, permission);
         }

         if (!all_allowed) {
             if (name.equals("*"))
                 all_allowed = true;
         }
     }

     /**
      * Determines if a set of permissions implies the permissions expressed in
      * <code>permission</code>.
      *
      * @param permission The Permission object to compare.
      *
      * @return <code>true</code> if <code>permission</code> is a proper
      * subset of a permission in the set; <code>false</code>
      * otherwise.
      */

     public boolean implies(Permission permission) {
         if (!(permission instanceof ServicePermission))
             return (false);

         ServicePermission sp = (ServicePermission) permission;
         ServicePermission x;

         int desired = sp.getMask();
         int effective = 0;

         // short circuit if the "*" Permission was added
 if (all_allowed) {
             x = (ServicePermission) permissions.get("*");
             if (x != null) {
                 effective |= x.getMask();
                 if ((effective & desired) == desired)
                     return (true);
             }
         }

         // strategy:
 // Check for full match first. Then work our way up the
 // name looking for matches on a.b.*

         String name = sp.getName();

         x = (ServicePermission) permissions.get(name);

         if (x != null) {
             // we have a direct hit!
 effective |= x.getMask();
             if ((effective & desired) == desired)
                 return (true);
         }

         // work our way up the tree...
 int last, offset;

         offset = name.length() - 1;

         while ((last = name.lastIndexOf(".", offset)) != -1) {

             name = name.substring(0, last + 1) + "*";
             x = (ServicePermission) permissions.get(name);

             if (x != null) {
                 effective |= x.getMask();
                 if ((effective & desired) == desired)
                     return (true);
             }
             offset = last - 1;
         }

         // we don't have to check for "*" as it was already checked
 // at the top (all_allowed), so we just return false
 return (false);
     }

     /**
      * Returns an enumeration of all the <code>ServicePermission</code>
      * objects in the container.
      *
      * @return Enumeration of all the ServicePermission objects.
      */

     public Enumeration elements() {
         return (permissions.elements());
     }
 }

